Cytochemical study on human spermatozoa metabolism during in vitro capacitation

In eutherian mammalian spermatozoa the capacitation is coupled to a specific type of metabolism, that is glycolysis or oxidative respiration. A cytochemical study was carried out on cytochrome oxidase and lactate dehydrogenase in human spermatozoa collected at different times during in vitro capacitation. Human spermatozoa were incubated in Biggers, Whitten and Wittingham's medium supplemented with 15% heat-inactivated human serum. Both histoenzymological reactions based on oxidative polymerization of diaminobenzidine (cytochrome oxidase) or on tetrazolium salts reduction (lactate dehydrogenase) can be quantitated and have been evaluated by microdensitometric method (Vickers M85). The results suggest that human spermatozoa depend almost quite on the anaerobic glycolysis during in vitro capacitation.